Dry cleaning process



May 19, 1970 P. R. DIXON ET AL 3,512,923

' DRY CLEANING PROCESS Filed Feb. l?, 1969 2 Sheets-Sheet 1 FIG. 2

DEN D COP K 2 Pmfwwmjwwm ATTORNEYS May 19, 1970 P. R. DIXON ET Al-3,512,923

DRY CLEANING PROCESS Filed Feb. 17, 1969 2 SheetS-Sheet 2 FlG. 3 25INVENTORS PETER R. DIXON ALBEN D. COPPOCK United States Patent Oce3,512,923 Patented May 19, 1970 3,512,923 DlRY CLEANING PROCESS Peter R.Dixon, Whittier, and Alden D. Coppock, Hacienda Heights, Calif. (both of617 W. Olympic Blvd.,

Montebello, Calif. 90640) Continuation-impart of application Ser. No.545,544, Apr. 27, 1966. This application Feb. 17, 1969, Ser. No. 799,764

The portion of the term of the patent subsequent to Mar. 11, 1986, hasbeen disclaimed Int. Cl. D06l l 02; D06f 46/00 U.S. Cl. 8-142 6 ClaimsABSTRACT OF THE DISCLOSURE A dry cleaning process wherein soiledarticles are placed in an air-impermeable chamber together with aquantity of a substantially dry cleaning agent which comprises apulverized carrier impregnated with a liquid cleanser; next, the soiledarticles are agitated together with a cleaning agent for a period oftime sufficient for cleaning; and, thereafter, the cleaning agent isseparated from the cleaned articles. Apparatus for practicing theprocess includes a circumferentially perforated cylindrical drum, openat one end and rotatable about a substantially horizontal axis, mountedwithin a vacuum chamber; means for maintaining the dry cleaning agentwithin the drum during the cleaning step; a fan having an inlet into thevacuum chamber for evacuating the dry cleaning agent from the drumduring the separation step; and, a filter for collecting the evacuateddry cleaning agent.

Cross-reference to related application The present application is acontinuation-in-part of copending application Ser. No. 545,544, filedApr. 27, 1966 now U.S. Pat. No. 3,432,253.

Background of the invention The present invention relates to a drycleaning process and apparatus and, more particularly, to a process andapparatus for cleaning articles of natural and synthetic materials in acontrolled environment with a substantially dry cleaning agent.

Standard dry cleaning processes utilize non-aqueous liquid solvent bathsin which a soiled article is immersed and agitated for an extendedperiod of time, much in the manner of the well-known cycle of a homewashing machine. Since the soiled article is necessarily soaked in theliquid solvent during the cleaning step, the standard dry cleaningprocess includes a high temperature drying step during which theresidual solvent is driven off and the clean article is deodorized.During this sequence, fabric may be damaged by constant abrasion, thearticle may shrink, often in a non-uniform manner if the articlecomprises dissimilar materials as in the case of fiberglass draperiesstitched together with non-fiberglass threads, and the article mayotherwise be deformed by the action of the relatively dense liquidsolvent and by tangling with other articles being cleaned at the sametime. In addition, liquid cleaning solvents may affect adversely brightcolors or impart a yellow tinge to some finishes, remove natural oilsfrom natural fibers which shorten useful life, and may otherwise imparta harsh feeling to the cleaned article. Finally, many such solventsrepresent substantial fire and health hazards. Accordingly, after havingbeen cleaned by a conventional solvent-bath process, an articlegenerally requires stretching, steaming or blocking to restore itsoriginal shape.

Conventional dry cleaning apparatus includes a chamber partially filledwith solvent in which soiled articles are immersed and agitated by arotating drum. Used solvent is drawn off into a storage tank and iseventually pumped into a filter which separates out undissolved soil.Periodically, the solvent must be distilled to eliminate dissolved soil.The complexity, bulk, and expense of the conventional dry cleaningapparatus limits its suitability to commercial establishments.

Prior attempts at avoiding dry -cleaning with a liquid solvent have beenlimited primarily to cleaning of furs as exemplified by U.S. Pat. No.1,747,324 which discloses the concept of placing a soiled article in aflexible porous bag together with a cleaning agent comprising a quantityof sawdust, which previously had been saturated with a given quantity ofliquid cleaning solvent. The soiled article and the cleaning agent,confined together in the bag, are agitated to achieve cleaning byintimate Contact of the two. Finally, the cleaned article is removedfrom the bag and the cleaning medium separated therefrom. The prior artdid not disclose or suggest, however, that the soiled article and thepulverized cleaning agent be agitated in an airimpermeable environmentto prevent evaporation of the volatile liquid cleanser which results ina rapid and substantial loss of cleaning ability. In addition, theporous bag used in the prior art did not retain a substantial amount ofair, and tended to collapse, hindering the free circulation of thecleaning agent and not serving to cushion the contents from externaljolts and impacts during agitation by tumbling.

Summary of the invention The present dry cleaning process comprisesplacing into an air-impermeable chamber a soiled article and a suitablequantity of a substantially dry cleaning agent which includes carrierparticles impregnated with a cleanser. The chamber is sealed to confinetherein the soiled article, the cleaning agent and a quantity of air.Thereafter, the soiled article and the cleaning agent are agitated inintimate contact for a period of time sufiicient to permit the removalof a substantial amount of soil from the article. When cleaning iscomplete, the cleaning agent is separated from the article.

An apparatus for practicing the present process comprises a drum housingdefining a vacuum chamber including a circumferential peripheral surfaceand axially spaced end walls. A cylindrical, circumferentiallyperforated drum, open at one end and rotatable about a substantiallyhorizontal axis, is mounted within the vacuum chamber. The drum rotatesrst to agitate soiled material and dry cleaning agent containedtherewithin and then to separate the dry cleaning agent from the cleanedmaterials. A blower has an inlet in the vacuum chamber for evacuatingthe dry cleaning agent through the circumferential perforations of thedrum during separation of the dry cleaning agent and the cleanedmaterials. Filtering means collect the evacuated dry cleaning agent.

In contrast with standard solvent-bath dry cleaning processes, thecleaning process of the present invention efficiently removes soil anddirt from substantially all types of clothing and other articles uponwhich the carrier particles will not become entrapped, includingpillows, lamp shades and draperies, without leaving a cleaning solventresidue, without shrinking, deforming, damaging or discoloring thefabric, and in a substantially more economical manner.

Unlike prior art fur cleaning processes, the present process utilizes anair impervious chamber during cleaning which substantially eliminatesevaporation loss of the impregnated cleanser and maintains theeffectiveness of the cleaning agent for as long a period as necessary.In addition, if a sealed, air-imprevious, fiexible bag is used tomaintain a sufficient amount of cleanser in association with thecarrier, a further advantage of friction and deformation reducingcushioning is obtained. Articles cleaned in this manner remain firm, yetsoft and pliable and usually do not require pressing, steaming andstretching. Finally, the cleaning action of the present process does notremove flameproong, waterproofing or other resins and coatings from mostmaterials.

Brief description of the drawings FIG. 1 is a front elevation in partialsection of the present dry cleaning apparatus;

FIG. 2 is a sectional view taken substantially along line 2-2 of FIG. 1;and

FIG. 3 is a side elevation in partial section of the present drycleaning apparatus.

Description of the preferred embodiment In the process of the presentinvention, a soiled fabric article is placed in a substantiallyair-impermeable chamber such as a horizontally rotatable drum or areusable, flexible bag of polyethylene or other suitable material. Next,a quantity of a substantially dry cleaning agent which includes apulverized, granular carrier impregnated with a suitable liquid cleanseris deposited in the chamber around the soiled article. The carrier maycomprise milled natural or white corncob dust, sawdust, or othersuitable material, but, corncob dust is preferred to sawdust because theformer is substantially free of natural oil. The corncob dust particlesize should range from to 200 mesh and preferably from to 175 mesh as ithas been found that particles too much ner than 100 mesh are difncult toseparate from fabrics and particles too much coarser than 100 mesh donot clean as well as the finer grades. If sawdust is employed, particlesize should range from approximately 40 to 100 mesh. In general, surfacewetting of the carrier particles with cleanser, not through saturation,is desired. The carrier should not be saturated with cleanser to theextent that the ability of the carrier should pick up dirt and oil froma soiled article is impaired. However, the carrier should be impregnatedwith cleanser to the extent that the particles remain sufiiciently moistthroughout the cleaning step. For example, a suitable cleaning agent maybe obtained by mixing two parts by weight of corncob dust carrier andfrom one to two parts by weight of a cleanser comprisingtetrachlorethylene, formaldehyde, silicones and detergents. Excellentcleaning may -be obtained by adding approximately eight to sixteenounces of the above cleaning agent per pound of soiled articles.

Thereafter, the chamber is sealed or otherwise made substantiallyairtight to conine therein the soiled fabric article, the cleaning agentand a quantity of air. The cleaning agent maintained in close proximityto the soiled article within the chamber to produce a particularlyeffective cleaning action. Additionally, the flexible, air-impermeablebag, if employed as the chamber, restrains the contained article tominimize working and prevents the article from being stretched out ofshape by tangling with other articles. Furthermore, the air conned ineach flexible bag cushions the contents to reduce substantially wearwhich necessarily results in conventional loose tumbling methods.Sufficient air should be retained in the exible, air-impermeable bag toinsure against its collapse and to permit free circulation and intimateassociation between the contained article or articles and the cleaningagent and to provide free space within the bag sufficient to allowgentle tumbling of the contained article or articles. In some instances,it may be necessary to expand the bag with compressed air to achieveproper cushioning and sufficient internal free space. In general, thebag should be inflated to provide an overall internal volume of from sixto eight times greater than the volume occupied by the contained articleor articles. Cushioning may be enhanced by employing a double-walledbag` which retains an additional amount of air `between the respectivewalls.

The soiled articles and the cleaning agent are agitated thoroughly for aperiod of time sufficient to elfect the removal of a maojrity of soilfrom the contained fabric articles. During this time, the cleaning agentcirculates throughout the sealed chamber in intimate contact with thefabric surface-s and a fraction of the volatile cleanser evaporates andcirculates throughout the sealed bag to aid in cleaning the containedarticles. The combined action of the pulverized cleaning agent and theevaporated cleanser loosens dirt and other soil which eventually adhereto and are lifted away by the cleaning agent carrier. Substantially allof the volatile cleanser is retained and conserved in theair-impermeable chamber either in a liquid or a vapor state. Thefraction of the cleanser which evaporates, saturates the air in thecharnber and establishes a dynamic equilibrium between the respectiveamounts of cleanser in the liquid and vapor state. Because the carrierhas been impregnated with an amount of cleanser su'icient to maintainthe cleaning agent in a properly moistened condition throughout theentire cleaning step, even subsequent to evaporation, optimum cleaningis achieved.

The cleaning step of the present process may be carried out in ahorizontally rotatable drum which should be -substantially airtightunless an air-impermeable, flexible bag is used. A drum rotating atabout 40 r.p.m. will suiciently agitate the contained soiled articlesand cleaning agent to achieve satisfactory cleaning within forty-tive tosixty minutes. Cleaning action may also be achieved by circulating theair within the chamber at high velocity to agitate the contained soiledarticles and cleaning agent. The cleaning step is preferably carried outat room temperature.

Upon completion of the cleaning step, air is circulated within thechamber at sufficient velocity to separate the volatile cleanser and thecarrier from the cleaned articles. The separation may be facilitated byagitating the cleaned articles as by tumbling within the chamber and byutilizing a warm air stream of approximately F. to F. Warm airaccelerates evaporation of the volatile cleanser which causes thecarrier particles to dry out more rapidly. Dry carrier particles do nottend to adhere to fabric surfaces and may be separated quite readily. Ifthe air-impermeable bag is used, separation is achieved by opening thebag, removing the contents and tumbling them loosely in a rotating drumin the presence of an air stream. If a heated air stream is notavailable, separation may be facilitated by hanging the articles looselyoutside the drum for several minutes to accelerate evaporation of thevolatile cleanser. Alternatively, separation of the cleaning agent fromthe cleaned articles may be achieved by forced air blasting cleanedarticles which are hung loosely to expose substantially their entiresurface area. This technique which is particularly suitable for use bycommercial establishments, has enabled the separation of cleaning agentfrom draperies within one minute. Incorporation of means for vibratingthe cleaned articles they pass under the air blast, such as vibratingconveyor rack upon which the articles are hung, will further decreasethe time consumed in removing the cleaning agent. Upon separation, thespent cleaning agent is collected by a suitable lter or trap foreventual disposal.

Referring to FIGS. 1 through 3, apparatus for practicing the present drycleaning process comprises a support frame 10. A housing which denes asubstantially airtight vacuum chamber 11 is mounted within the supportframe 10 and includes a. circumferential peripheral surface 12 andaxially spaced end walls 14, 15. In the present embodiment, the end wall15 includes a door 16 mounted in airtight relationship to provide accessto a cylindrical drum 17 which is rotatably mounted within the vacuumchamber 11 on a substantially horizontal drive shaft 18. The drum `17 isopen at an end adjacent the access door 16 and has a multiplicity ofperforations 20 in its circumferential surface 21.

A motor 23 provides torque for the drive shaft 18 of the drum 17 througha belt and pulley system 24 or other suitable transmission. Preferably,the drum 17 rotates unidirectionally at about 40 r.p.m. but it iscontemplated that the transmission may be modified to provide successivereversal of the direction of rotation of the drum 17 upon completion ofeach revolution. The duration of the cleaning and separation cycle isdetermined by a timer control 25 mounted on a panel 26 of the supporthousing 10.

A blower 30 has an inlet 31 through which is drawn air from the vacuumchamber 11 and an exhaust 32 to be outside through conduit 33. The airliow rate within the vacuum chamber 11 is regulated by an adjustabledamper 36 which includes an inlet 37 from the surroundings and an outlet38 into the vacuum chamber 11. The damper 36 may be adjusted by acontrol 39 mounted on the panel 26. A lilter 41 is provided up streamfrom the inlet 31 of the blower 30 to collect the granular cleaningagent and to prevent it from passing through and damaging the blower 30.

Finally, an electric heating coil 45, mounted on the exterior surface ofthe -vacuum chamber 1.1, regulates the temperature within the chamber1-1 by adjustment of a thermostatic control 46 mounted on the panel 26.The coil 45 should be sealed and insulated from possible contact withthe granular cleaning agent which may tend to ignite upon contact with ahigh temperature body.

In operation, an air-impermeable bag, lsuch as that previouslydescribed, is illed with soiled articles, cleaning agent and a properamount of air, sealed and deposited in the drum 17 through lthe accessdoor 16. Controls 25, 39, yand 46, are preset as required by the Weightand nature of the article or articles to be cleaned. The motor 23 isactivated to rotate drum 17 which causes the bag to be tumbled gently,agitating the contained articles and the cleaning fagent in the mannerpreviously described. Upon completion of the cleaning step, the motor 23is deactivated and the contents of the bag are emptied loosely into thedrum 17. Upon reactivation of the motor 23, the drum 17 rotates tofacilitate separation of the cleaning agent from the cleaned articles.The blower 30 and the electric heating coil 45 are activatedsimultaneously, the former to provide forced air circulation within thevacuum chamber 11 and drum 17 of suicient velocity to evacuate thecleaning agent through the circumferential perforations 20 and thelatter to maintain the temperature within the vacuum chamber 11 atapproximately 110 F. to 120 F. The pulverized, granular carrier iscollected in the lilter 41 and the vaporized cleanser is exhaustedthrough the conduit 33 either for safe disposal or for condensation andreuse.

Alternatively, it is contemplated that the drum 17 of the presentapparatus may be modified to enable the retention therewithin of thegranular cleaning agent during the cleaning cycle, thereby eliminatingthe necessity of using the tlexible, air-impermeable bag. Such anarrangement is particularly desirable for non-commercial machines wheredeformation and friction wear of soiled 'articles is not as pronounced.

We claim:

1. A dry cleaning process comprising the steps of:

(a) inserting into an air-impermeable chamber a soiled article and asuitable quantity of a substantially dry cleaning agent including apulverized granular carrier impregnated with a cleanser;

(b) sealing the chamber to confine therein the article,

the cleaning agent and a quantity of air;

(c) agitating the isoiled article and the cleaning agent for a period oftime sutiicient to etlect the removal of a majority of the soil from thearticle; and

(d) separating the cleaning agent from the article.

2. A dry cleaning process according to claim 1 wherein the pulverizedgranular carrier is impregnated with suicient cleanser to maintain thecarrier moist during step (c) without impairing the ability of thecarrier to pick up soil from the article.

3. A dry cleaning process according to claim 1 wherein the cleaning'agent is separated from the article during step (d) by air circulatingat a substantial velocity.

4. A dry cleaning process according to claim 3 wherein the temperatureof the circulating air is maintained at approximately F. to 120 F.during step (d) to facilitate the separation of the cleaning agent fromthe article.

5. A dry cleaning process according to claim 3 wherein the article isagitated during step (d).

6. A dry cleaning process according to claim 5 wherein the article isagitated during step (d) by tumbling.

References Cited UNITED STATES PATENTS 2,316,386 4/ 1963 Albrecht 8-1423,151,345 10/1964 Massop 8-142 XR 3,432,253 3/ 1969 Dixon et al. 8--142MAYER WEINBLATT, Primary Examiner U.S. Cl. X.R.

